1. Field of the Invention
This invention relates to producing lower molecular weight hydrocarbons; specifically it relates to processing naphtha utilizing a high shear device.
2. Background of the Invention
Conventionally, the process of cracking hydrocarbons is dependent on temperature and optionally, the exposure of reactants to catalysts. The process cleaves higher molecular-weight, longer chain, heavy hydrocarbons to form low molecular-weight, short-chain, light hydrocarbons. These light hydrocarbons may be further refined for liquid fuels and other applications.
Liquid naphtha is obtained in petroleum refineries as one of the intermediate products from the distillation of crude oil and is used as a feedstock for olefin (ethylene and propylene) production. Naphtha is often cracked by a process commonly referred to as steam cracking where steam is injected into the liquid naphtha and briefly (milliseconds) heated to high temperatures (800° C.-900° C.), whereby it is cracked into lighter components including olefins. Steam cracking of naphtha produces a mixed stream of light hydrocarbons that includes very desirable ethylene and propylene components.
However, steam cracking of naphtha is an energy intensive reaction. For example, mixing high temperature steam with the naphtha, maintaining the temperature and reactor residence time represent energy costs associated with steam cracking. Additionally, in order to control the light gas product composition, cracking efficiency, and minimize coking, the severity or temperature of the reaction requires control of a narrow range of operational parameters. Any parameter of the reaction occurring outside this optimal range results in potential loss of the light gas products, revenue, and profit.
There is a need in the industry to reduce energy consumption and increase the yield of higher value components such as ethylene and propylene from steam cracking. There is also a need to reduce coking of steam cracking furnaces that results in costly downtime, increased maintenance, and lost efficiencies.